There is a well-established research literature documenting large, persistent, and expanding socioeconomic gradients in health. While early work focused on documenting the contours of health gradients across a wide array of health outcomes and the multiple dimensions of socioeconomic position, much of the effort over the past decade has focused on trying to understand the causal processes that underlie disparities. Two important and related, though rarely integrated, lines of research on the causes of health gradients are a) cross-national investigations of inequalities and b) life- course/developmental perspectives that have investigated the long-term impacts of childhood health insults and socioeconomic disadvantage. Each of these lines of research has provided important insights into the social and life course processes that generate socioeconomic inequalities in health. However, researchers working in each of these areas have tended to pay scant attention to the other. The current project integrates these two complementary approaches using existing NIA-supported data from 17 countries to investigate the role of early life health and socioeconomic disadvantage in generating socioeconomic gradients in health across international contexts.